Carbon capture and utilization from an ethylene oxide plant for sustainable urea production: techno-economic...

It is essential to establish a carbon dioxide (CO₂) capturing unit for recycling and repurposing CO₂ that is released into the atmosphere in the petroleum refinery and petrochemical plants. This will reduce the environmental impact of these processes and create additional value. The present study investigates two possible pathways for carbon capture from an ethylene oxide (EO) production plant for utilization in a urea plant. The simulation of the proposed processes was carried out using Aspen Plus software, and the optimization of the transportation pipeline was performed using Matlab and Aspen Hysys software. Two different scenarios were investigated for the removal of water from CO₂. In the first scenario, a two-phase separator was utilized to separate the accompanying water from CO₂, whereas the second scenario incorporated a reactive distillation tower (RD). The proposed scenarios were evaluated and compared from technical, economical, and environmental perspectives. The results obtained from the simulation showed that the second method eliminated the risk of corrosion in gas transmission pipeline by implementing a RD tower, which converts accompanying water into ethylene glycol (EG) through a reaction with ethylene oxide. Therefore, the gas transmission pipeline material could be carbon steel instead of stainless-steel, that was the case for the first scenario. On the other hand, the first method had lower energy consumption, resulting in 37% lower CO₂ emissions compared to the second method. Furthermore, the total operating cost (TOC), total capital cost (TCC), and total annual cost (TAC) associated with the separation of accompanying water and transportation pipeline were evaluated for each scenario. The revenue from ethylene glycol production in the second scenario was also calculated. In summary, the results indicated that the second scenario outperforms the first scenario from the economic viewpoint. In contrast, the first scenario is more environmentally favorable in terms of CO₂ emissions.